A collapse zone is an area around a
structure, usually a
burning structure, that may suffer
structural collapse
Structural integrity and failure is an aspect of engineering that deals with the ability of a structure to support a designed structural load (weight, force, etc.) without breaking and includes the study of past structural failures in order to ...
. A collapse zone affects
firefighters working on the exterior of a structure.
Signs of structural failure
The first indicator of possible structural failure is the type of
wall
A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including:
* Walls in buildings that form a fundamental part of the sup ...
. The material of the wall may provide clues, as well as the structural significance. A free-standing wall has a higher collapse risk than a non-bearing wall.
Other indicators include:
*
smoke
Smoke is a suspension of airborne particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-produc ...
from
mortar joint
In masonry, mortar joints are the spaces between bricks, concrete blocks, or glass blocks, that are filled with mortar or grout. If the surface of the masonry remains unplastered, the joints contribute significantly to the appearance of the mas ...
s
*bowing walls
*other areas of structural failure
After an interior collapse, the risk of an exterior collapse, and therefore the need for a collapse zone, rises significantly.
Structural failure
A wall may collapse in three general manners.
90° angle collapse
This is the most common type of structural collapse. It is similar to a falling tree. The wall falls straight out and the top hits the ground at a distance equal to the height of the wall.
Curtain-fall collapse
This type of collapse generally occurs with a masonry wall. It collapses like a
curtain
A curtain is a piece of cloth
Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fa ...
dropping from the top, creating a pile of debris at the base of the wall.
Inward/outward collapse
A wall leaning inward may not necessarily fall inward. The lower or upper portion may slide or "kick" outward.
Establishing a collapse zone
Collapse zones are traditionally established by a commanding officer. The collapse zone itself should be as wide as the structure and as tall, plus half the height. The reason for this increase in height is that the worst-case scenario (and the most common), a 90° Angle Collapse, must be assumed. A collapse zone should be established with
barricade tape and should be enforced if necessary.
Obstacles
A collapse zone can easily limit the access of
hose lines. Hose lines should operate outside the zone, on the sides. A secured (and unattended)
deluge nozzle can also be put into operation, with caution. An
aerial fire apparatus
Aerial may refer to:
Music
* ''Aerial'' (album), by Kate Bush
* ''Aerials'' (song), from the album ''Toxicity'' by System of a Down
Bands
* Aerial (Canadian band)
* Aerial (Scottish band)
*Aerial (Swedish band)
Performance art
*Aerial silk ...
may be required. In this case, the collapse zone should be considered a three-dimensional arc, and aerial ladders may not operate in that arc.
References
{{reflist
Firefighter Close Calls.com Vol. 9, No. 107
Firefighting